Studies have suggested that emissions systems can be deactivated as a result of contamination from compounds derived from the engine oil. Other studies have suggested that emissions system durability may be improved by using lubricants containing high metal/phosphorus ratios. Reducing the level of phosphorus in the engine oils has also been suggested as a means of prolonging the efficiency of the catalytic converter. The phosphorus in engine oils originates primarily from zinc dialkyldithiophosphates (ZDDP's), which are used to prevent wear and control oxidation. Over the years ZDDP's have demonstrated reliable anti-wear and antioxidant effectiveness. Most engine builders would not recommend engine oils which contain substantial reductions from today's ZDDP levels without extensive proof in the laboratory and the field that wear protection is acceptable. Commercial engine oils meeting API SJ requirements usually contain approximately 0.10 wt. % phosphorus derived from ZDDP. A substantial reduction in ZDDP's, which may be required for catalytic converter durability, would result in significantly higher engine wear and oil oxidation. To compensate for the use of less ZDDP in engine oils, supplemental wear and oxidation inhibitors are required.
Dithiocarbamates have been known in the art for some time. Examples of various structurally different dithiocarbamates are disclosed in the following patents:
3,407,2225,693,5984,885,3654,125,4795,902,7763,867,3595,686,3974,836,9424,758,3623,509,0512,710,8725,789,3574,927,5525,629,2723,356,7025,840,6644,957,6434,876,3755,759,9654,098,705All patents, patent applications, and articles or publications are incorporated herein by reference for their full disclosure.
Examples of alkoxy- and hydroxyl-substituted dithiocarbamates are known in the art and examples are disclosed in the following references: Zh. Org. Khim. (1991), 27(1), 161-170; Zh. Org. Khim. (1988), 24(2), 286-291; Z. Chem. (1987), 27(1), 24-25; Zh. Org. Khim. (1985), 21(6), 1173-1176; Neftekhim (1983), 23(3), 409-412; and Neftepererab. Neftekhim. (Moscow) (1983), (1), 20-22.
Methods of producing alkylglycidyl thioethers are reported in U.S. Pat. Nos. 4,931,576 and 5,618,778.
Examples of commercially available dithiocarbamates include Vanlube 7723, a methylenebis(dibutyldithiocarbamate), Molyvan A, a molybdenum oxysulfide dithiocarbamate, Molyvan 822, an organo molybdenum dithiocarbamate, Vanlube AZ, a zinc diamyldithiocarbamate, Vanlube 71, a lead diamyldithiocarbamate, Vanlube 73, an antimony dialkyldithiocarbamate, and Vanlube 732, a dithiocarbamate derivative, all obtained from R.T. Vanderbilt Company, Inc.